Spectrum

Interest: Massive. Probably has the largest selection of adventure games
for any computer. World of Spectrum lists over 2,000 games!

Games

World
of Spectrum - a fabulous site and the only Spectrum page you'll ever want to
visit. Run by Martijn van der Heide. This site has the largest number of adventure
games for any computer anywhere on the net!

The TZX Vault does a terrific job of preserving Spectrum software, including rare adventure games.

Zenobi - the publisher
of more than 200 text adventures has an informative site here. They sell all
their games on a cd for a mere £5, so if you enjoy Zenobi's adventures, I strongly
urge you to support them in this manner.

Apple II

Interest: Large. The selection isn't as huge as for C64 or Spectrum,
but since the games only come on disks, they generally tend to be quite large.
In addition, they load a great deal faster than their C64 disk counterparts.
Unfortunately, the Apple II emulation scene isn't exactly teeming with life.

Oric

Interest: Small-medium. The range of games available is fairly small and many
of them are quite primitive. There are, however, a number of games for Oric
that weren't released in other formats, including many titles in French. The emulation scene seems very limited.

TRS-80

Greg Hassett, one of the pioneers of the early adventure scene, wrote a number
of Scott Adams-like adventures for the TRS-80. Other than that, I really don't
know much about this machine. Check www.trs-80.com/
for further info.